Glass window jalousies and metal wall louvers usually include a rectangular frame and a plurality of elongated louver blades extending horizontally from one vertical side member of the frame to the other. Means are provided for pivotally mounting the blades between the side frame members and for rotating them in unison between closed and open positions.
A persistent problem with such louver assemblies has been leakage of air, rain, snow and the like between the side frame members and their adjacent louver blade ends. In colder climates, storm windows are often installed to stop such air flow, but this eliminates opportunity to ventilate through the louvers while the storm windows are in place. In warmer climates, complete blockage of air flow could not be achieved at any time. This occasions severe and unacceptable heat and energy losses during cold weather; and similar energy losses in hot weather when air conditioning is being used.
The prior art reveals several attempted solutions. U.S. Pat. No. 2,390,394 granted to Smith on Dec. 4, 1945, for example, describes a louver arrangement including a plurality of glass plates horizontally arranged between two side frame members. A disc is attached to each end of the glass plates, each disc being rotatably mounted with respect to one of the opposing side frame members. Felt strips secured to each side frame member between each disc and the side frame member provide a means for sealing the window against air passage. This structure is cumbersome and expensive and can develop high friction against louver movement.
In U.S. Pat. No. 2,394,059 to Hite, granted Feb. 5, 1946, glass louver blades are supported horizontally between two opposing vertical guides of a frame. Each louver blade is supported at its transverse ends by an end holder, each end holder being pivotally mounted with respect to one of the vertical guides. A packing strip is mounted in each end holder and projects laterally beyond the end holder edge to engage with the adjacent vertical guide to form a joint. The packing strip is felt, rubber, asbestos or the like. The structure suffers from the lack of resilient means to positively engage the sealing member between the blade end and the vertical guide without unduly increasing the friction to blade movement. The seal will be at its best (and friction highest) when first installed. As the packing strip ages and weathers, the seal progressively deteriorates over the entire life of the shutter structure.
In U.S. Pat. No. 3,894,481, granted to Alley on July 15, 1975, a multi-blade damper is shown having a plurality of rectangular blades mounted in a rectangular frame on transversely extending parallel shafts. The ends of each movable blade carry a sealing flap rigidly attached and extending longitudinally beyond the blade edges into sliding surface contact with the vertical side channels of the frame. The flaps are constructed of resilient material. No positive means of insuring good contact as the unit ages is provided. Also the area around the pivot shaft is not sealed.
In U.S. Pat. No. RE 23,182 to Cooper reissued Dec. 13, 1949 on original grant of Jan. 4, 1949, the louver blades are pivotally mounted at each end to a vertical metal fitting having a face portion abutting the blade edges and two outer edge flange portions abutting the vertical sides of the window frame. Holes in the metal fitting are adapted to receive channeled end members which support the louver blades. Each channeled end member has a protecting metal strip pivotally attached at one end to a bridging member. Vertical movement of the bridging member causes all louver blades to rotate in unison about their respective pivot points. When the louver assembly is in the closed position, the bridging member occupies the space between the metal fittings and the channeled end members, overlapping the protecting strip and the metal fitting. As seen in FIG. 3 of that patent, for example, no positive seal is achieved. The structure is awkward and expensive.
The general idea of inserting a flexible side sealing member between frame side members and the associated transverse louver blade ends is shown in U.S. Pat. No. 3,372,514 granted to Adams on Mar. 12, 1968. A side sealing member is positioned between the ends of the louver blades and each vertical side frame member. Each side sealing member has a generally U-shaped cross sectional configuration and includes a central web portion facing inward toward the blade ends. Two flanges are directed outward toward the vertical side member. The edges of the flanges are meant to engage with the surface of the side frame member while the central web portion is meant to engage with the ends of the louver blades. The side sealing members are formed from a flexible material such as Phosphor bronze. The purpose of the invention is to "minimize light leaks and to . . . minimize ingress of wind, rain, snow and debris." No Claim is made to positively seal against air passage and no positive means is provided to keep the U-shape sealing member flat enough to continue to provide a positive end seal as time and weather takes its toll. As long as the flanges hold up no center seal need be maintained to provide a light shield, and there will be no disadvantage to the structure when the face of the sealing member becomes concave as it will in time.
The Smith, Hite and Alley louver assemblies share the problem of requiring contact between a rigid surface and a soft or elastic material. Wear to the elastic or softer material is caused by rubbing contact with the rigid surface whenever the louver blades are moved. Eventually this damages the elastic material and leakage results. Cooper avoids this problem by including only substantially rigid materials in his louver assembly. A problem with Cooper, however, is the close manufacturing tolerance required to form the sliding but snug contact between the bridging member and the metal fitting.
In the Adams device, there is no support for the central web portion, as the side sealing member is supported against the side frame member solely by the two outside flanges. With the louver assembly closed, the pressure from the louver blades acts principally upon the center of the web. The resulting tendency, in the flexible side sealing member, to deform concavely with respect to the blade edges tends to hinder pivotal movement of the blades if a contact with the blade ends persists, and to allow air passage if not.